The use of modern, easy-to-clean, prefabricated kitchen, bathroom, and cellar furnishings, furniture with plastic veneer, and the increasing use of freezer chests, refrigerators, washers and dishwashers, that is, household appliances with enameled metal walls with large surfaces, have led to a steep increase in the demand for all-purpose liquid cleaners in the household.
General purpose or all-purpose household cleaning compositions for hard surfaces such as metal, glass, ceramic, plastic, and linoleum surfaces have been sold commercially in both powdered and liquid form. The powdered compositions consist mainly of builders and buffering salts such as phosphates, carbonates, silicates, and the like and these compositions are diluted with water prior to use. While use concentrations of such compositions usually provide good inorganic soil removal, they tend to be deficient in removal of organic soils such as the greasy/fatty/oily soils typically found in the domestic environment.
On the other hand, all-purpose liquid cleaners have met with greater commercial acceptance because they have the advantage that they can be applied to hard surfaces in neat or concentrated form so that a relatively high level of surfactant material is delivered directly to the soils. Furthermore, it is easier to incorporate high concentrations of anionic or nonionic surfactant in a liquid rather than in a powdered composition. Because of these two significant advantages, much research and development effort has been expended on formulating all-purpose liquid cleaning compositions which are stable upon storage, have good physical properties and are effective in removing inorganic and organic soils.
Liquid hard surface cleaners generally have been classified into two types. The first type is a particulate aqueous suspension having water-insoluble abrasive particles suspended therein, which particles are palpable. Some of the cleaners of this type suffer a stability problem and other cleaners of this type have received poor acceptance by consumers because of their "gritty" feel which causes many people to be reluctant to use them for fear of scratching the surface to be cleaned. The second type is the liquid detergent without suspended abrasive and, seemingly, this latter type is preferred by consumers. While this second type generally is a mixture of surfactant and builder salt in an aqueous medium, the product formulations in the market place have varied widely in composition.
One liquid product which achieved some success was based upon a mixture of soap, alkylbenzene sulfonate and fatty acid alkanolamine plus inorganic builder salts. Such liquid exhibited good temperature stability and a desirable viscosity, but tended to exhibit cleaning disadvantages as compared with another product based upon a mixture of alkylbenzene sulfonate and ethoxylated alkanol plus builder salts. However, the latter composition usually requires a high concentration of a lower alkylbenzene sulfonate hydrotrope in order to achieve homogeneity in the presence of builder salts and the inclusion of hydrotrope resulted in lower viscosity and the need for thickening agents.
Other all-purpose liquid products were prepared which incorporated a solvent, such as a terpene. For example, German Patent Application No. 21 13 732 discloses the use of terpenes as anti-microbial agents in washing compositions. British Pat. No. 1,308,190 teaches the use of dipentenes in a thixotropic liquid detergent suspension based composition. German Patent Application No. 27 09 690 teaches the use of pine oil, a mixture of largely terpene alcohols, in liquid hard surface cleaning compositions. U.S. Pat. No. 4,414,128 teaches the use of terpenes with solvents of limited water solubility such as benzyl alcohol in all-purpose cleaning compositions. The terpenes are used to provide cleaning as well as to control sudsing. A similar composition is disclosed in European Patent Application No. 0080749 which comprises surfactant, terpenes, butyl carbitol and builder salts. Again, the terpenes are included for cleaning and as suds regulators.
Despite the extensive efforts in formulating all-purpose liquid cleaning compositions, there is still a need for a liquid product with effective cleaning properties, particularly in removal of grease and oily soil when applied neat. Also, such products should be effective at varying water hardness levels, should have desirable foaming characteristics and should leave little or no spots or streaks when rinsed or not. Furthermore, the resultant product should be homogeneous at temperatures from about 5.degree. C. to about 49.degree. C. and should exhibit a desirable viscosity.